text:
Why did the RAAF procure the F/A-18 despite being purpose-built for carriers?
Why did the Royal Australian Air Force (and others) procure the F/A-18 despite being purpose-built for carriers?

Worth noting that landlocked Switzerland also operates the F/A-18 https://en.wikipedia.org/wiki/List_of_aircraft_of_the_Swiss_Air_Force

Two reasons:
The airplane is extremely versatile, while having adequate performance, and is a good choice when a small airforce needs a do-everything airplane to replace multiple types.
Being designed for carriers, it's overbuilt for normal land operations in many key areas, which means a longer airframe structural life in its much easier life landing on runways.  For an air force with a limited budget and the need to run the airplane a long time, it's worth giving up some of the speed/payload/range that was sacrificed by the structural needs of carrier ops.

Don’t all airforces have a limited budget?

@Koyovis Most airforces have limited budgets - only when the governments funding them realize that the taxpayers' pockets aren't bottomless, and/or they actually care about not putting their country into incomprehensibly large debt.

@Koyovis  RAAF or RCAF compared to USAF?  A teeny tiny bit limited, in comparison.  USAF's "limited budget" still allows for numerous different types for different jobs.

@X-27 Yes. It was a rhetorical question.

There are a number of countries using the F/A-18.

Selection of the replacement of the Mirage III was of course carefully considered by the RAAF, and the most suitable airframe was considered for the mission and circumstances  typical for a vast, distant and sparsely populated continent:

The fact that it was designed for carrier operation actually was a plus, since it results in a more robust airframe with lower expected corrective maintenance costs.
It was a twin-engine design, and the most suitable one at the time. The distances between airfields are vast in Australia, and the experience with the single engine Mirage III was that too many were lost after an engine fail.

That raises the obvious question: is the F/A-18 ETOPS-certified?

Isn't ETOPS specific to passenger carrying aircraft?

ETOPS is more about how it's maintained, i.e. The same mechanic doesn't change all three oil debris detectors at once...

@Harper Correct operating procedures are necessary for ETOPS but most definitely not sufficient. Certifying new aircraft types for ETOPS is a major undertaking long before the maintenance guys get involved. Most of the maintenance issues are just "industry best practice" in any case - not that every airline in the world follows best practice, of course.

I assume their experience with single engine airframes is one of the major reasons they didn't go for the F-16?

@Mast Yes indeed, engine failure below 10,000 feet meant Eject according to this thread

The twin-engine argument is the same reason Canada opted for the F18 too - also a large country with few airfields.

Why a carrier-capable plane over a land-based plane?    Australia has a history of operating carrier craft beginning in the 1920s.
At the moment there are two helicopter carriers in the Royal Australian Navy, but no full-deck carriers since the retirement of HMAS Melbourne in 1982.
However, Australia is surrounded by a lot of water, and lacks land borders with any other nation.  (map below)  It is possible that carriers may return.
The F/A 18 had an estimated service life of 20 to 30 years (depends on the source) based on 100 carrier landings a year Source.  So its not unreasonable that a carrier could be ordered and delivered and commissioned while FA-18 were still serviceable.
The FA-18 order was announced on 20 October 1981,source which overlaps the in-service years of the HMAS Melbourne.

Yeah, but why do the air force uses the FA-18 instead of the navy which operates the carrier? I'm not even sure if their air force pilots are generally trained to land on carriers.

"a carrier could be ordered and delivered and commissioned while FA-18 were still serviceable." While that won't take 20 years, it does take long enough that I have my doubts about this being one of the reasons. By the time that carrier would arrive, the airframes would still be flying, yes, but for how long? Keep in mind carriers are intended for long service life too.

@Mast Fair point - there's also a "skill" or culture which once lost is hard to maintain.  I have no idea if landing a carrier-enabled fighter on land helps in any way with learning carrier ops later, so it didn't get into the answer, but I do know that once a skill is lost from a group (of pilots in this case) it is much harder to re-establish.

@Mast The decision to buy FA-18s was announced in October 1981. At that time, RAN was expecting to get a cheap deal on a second-hand carrier from Britain (Invincible, which was then only four years old). Had that worked out as planned, the new carrier would've been in service before the new FA-18s arrived - though as it turned out, the Falklands War scuppered that plan . The decision not to replace Melbourne wasn't finalised until 1983. (1/2)

@Mast Per Wiki, the RAAF FA-18s were modified to remove all equipment for catapult takeoffs, so they probably weren't intended for carrier use. But some of the options for replacing the Melbourne involved carrier-based FA-18s. (2/2)

For the "and others", the documents from Finland have become public as the secrecy period of 25 years has recently been passed.
In a major military deal, there are always technological, economical and political aspects.
There were five candidates:

Russian MIG-29
Swedish JAS 39 Gripen
French MIRAGE 2000-5
General Dynamics F-16 (USA)
McDonnell Douglas F/A-18 Hornet (USA)

The Finnish Air Force tested all candidates between summer 1991 and winter 1992. The Hornet was considered clearly better than the others. It had the best range, mission time and could carry the biggest missile load. These are important factors for Finland, which is geographically a large country.
Air Force saw Hornet as modern and it had good development potential. Development costs were shared by many nations.
F-16 did not fulfill all the performance requirements from the Air Force. In addition, proposed participation of the Finnish aviation industry was not seen as adequate. At the time of decision, the production line of F-16 was closing.
Gripen and especially many of it's critical components were still in prototype stage. The system was seen as too immature and hence the JAS was rejected as being too risky. Swedes expected that Finland would take part in the development costs, though it was not known how much costs there ultimately would be.
Mirage did fulfill Air Forces requirements and was considered as a really good plane for the pilot. However, the maintenance system was seen as difficult and it was feared that maintenance costs would be high due to low number of users.
MIG-29's electronics and maintenance systems did not fulfill requirements. Lifetime of the plane was half from that of the others. MIG-29 was by far most expensive considering both purchase price and operating costs over 30 year period.
Politically, buying the MIG would have meant co-operation between Finland and Russia, and this type of co-operation was seen as undesirable by the government. Selecting the F-18 was a decision and signal towards co-operation with the west. During the cold war Finland was not part of the eastern block, but being a neighboring country of Soviet Union, did experience quite a bit pressure from the east.
The Russian economic crash following the collapse of Soviet Union was a major issue, too. There was no guarantee that the country would be able to deliver the planes.
In hindsight, the decision to choose F/A-18 has been considered as excellent. Especially, the risks with JAS did realize, the offered B-version of the plane has been considered as a failure.
Source: https://www.iltalehti.fi/kotimaa/a/201707022200238131 (in Finnish)

Looks very similar to the Canadian decision (though they of course didn't consider the MiG-29 but the Tornado and F-15). Twin engines, cost, payload, endurance, were important. Tornado and Mirage were considered poor performers, F-15 too expensive, and F-16 and Gripen (I think it was considered, maybe it wasn't) lacking in range and payload capacity.

"At the time of decision, the production line of F-16 was closing." I'm not sure what you mean. F-16s were produced continuously until being paused in 2017 to move to a different factory.

@DavidRicherby "at the time of decision" refers to the information and plans available at the early 1990's. I suppose the plan then was to ramp down production, which indeed did not happen.

There is a very limited selection of affordable 2-engined fighter aircraft (and the selection was even more limited in the time frame of these acquisitions). Some countries (Canada, Australia) have large uninhabited areas and their air forces prefer the added safety of a second engine. This limited Australia's choices to F-15 or F-18.

Yes and no. The logical upgrade path from the Mirage III would have been the Rafale...

But that wouldn't be available for another 15 years (The Hornets entered service with the RAAF between 1984 and 1990, Rafale entered service in 2001)


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Are some tail wheels made out of solid plastic?
Are any tail wheels on small planes made of hard, rounded, plastic-like material?

Welcome to aviation.SE!

You can see that sort of thing on ultralights that land at 25-30 mph where they may use a solid once-piece wheel made of some elastomeric plastic or rubber.  Smaller airplanes however, will use a rubber tire on an aluminum wheel with proper bearings, due to the very high rolling RPM once you are landing above 40 mph (or at least a bushing that can take high speeds and loads).
The smallest ones usually have solid rubber tires and once you get to a certain size, say on airplanes over 1500 lbs or so, they will be pneumatic tires.  For example, an Aeronca Champ usually has a solid rubber tailwheel, but it's heavier and faster Citabria descendant has a pneumatic tailwheel tire.  You can browse typical tailwheel tires here.

$1,000+ for a solid rubby wheel on a caster. I should get into the niche aircraft parts business.

Once the part is "certified", triple the price. The extra money won't go in your pocket; it's eaten up in regulatory compliance costs.   You will notice that the uncertified homebuilt tailwheels are far cheaper because there are no regulatory hoops.

Quite a few sailplanes (e.g. Schweizer 2-22, 2-33) are currently equipped with plastic skateboard wheels for tailwheels, even though that may not have been the part that was originally prescribed.

source: Stack Exchange

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sort: votes


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What role did the RAT (Ram Air Turbine) play on US Airways flight 1549?
An article in June 2018 Flying Magazine regarding the RAT by a Rob Mark explains that Capt. Sullunberger deployed the RAT for additional power to guide the plane down to the safe ditching on the Hudson River.
My understanding is, according to all the narratives, the book, and the movie, what saved the day (with the exception of the amazing skills of the flight crew) was the immediate starting of the APU by Capt. Sullenberger that was not even on the QRM check list,...and not the RAT.
I am wondering if both (APU and RAT) were used on that flight or the APU only? And if so, has Flying Magazine author made a mistake?

The full NTSB report can be found here and is the official source of information on the incident. According to that report Sullunberger did immediately start the APU which did deliver power and they determined they did not need to manually deploy the RAT. However the onboard systems deployed it automatically likely as a result of the initial power loss and sufficient airspeed (over 100Kts).

Regarding step e, the pilots stated that they determined that
  electrical power was established and, therefore, that the RAT did not
  need to be manually deployed. Further, immediately after the loss of
  engine thrust, the captain started the APU.

This can be heard in the official transcript

At 1527:14, the first officer stated, “uh oh,” followed by the captain
  stating, “we got one rol- both of ‘em rolling back.” At 1527:18, the
  cockpit area microphone (CAM) recorded the beginning of a rumbling
  sound.
At 1527:19, the captain stated, “[engine] ignition, start,”
  and, about 2 seconds later, “I’m starting the APU [auxiliary power
  unit].”5
At 1527:23, the captain took over control of the airplane,
  stating, “my aircraft.”

However the RAT was found to be deployed (due to the automatic systems on the aircraft) when the airframe was recovered

When all of the airplane’s electrical power is lost and the airplane
  has an airspeed greater than 100 knots (kts), the RAT will
  automatically deploy and begin providing electrical power. The RAT was
  found in the extended position when the airplane was recovered from
  the water.

How can a pilot extend rat when there is no power? Which is the problem rat tries to solve. (afaik) Is there a handle directly attached to it?

@AliErdem: https://aviation.stackexchange.com/questions/1583/how-do-ram-air-turbines-get-deployed

If I recall correctly, you do not need power to deploy a RAT, you need power to retract it. Like brakes on a truck or a train, the default state is actually deployed, not stowed.

RATs are normally spring-deployed (to get them out fast), and are held in by a latch. You need battery power to a solenoid to release the latch - twang! (They are retracted by hand to ensure the latch is hlding correctly, to avoid a twang at the wrong time.)

Thank you for linking the report. It was an interresting read.

The RAT only delivers 5 kVA on the A320. It supplies electrical power only to the essential buses. Therefore the APU is still required to power the normal AC BUS bars and the DC buses via TRU's.

Before he decided to start the APU which needs power for the starter and some time to spool up and go online he was already on RAT provided power. As stated above if you loose both generators the RAT will deploy automatically in order to provide power to the busses. APU and its generator is just a good backup in case the RAT would fail. This one btw does not need AC but DC power to start the APU which is provided by the batteries or in this case inverters from AC bus bars when RAT is running.

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What does Line imply in Line Replaceable Unit?
Does line indicate the aircraft is lined up in hangar (!) and maintenance crew can replace it?
Or does it mean something else?
Wiki talks about operating location and distances.. What is that?

"Line" refers to "Air Line" or "Flight Line". It's the same "line" as when you refer to "line operations" or, for pilots, "line indoctrination". It basically means "in the operational world".
Line Replaceable generally means a system component (not structural) that can be changed anywhere out in the field, even in the middle of nowhere, by persons with the required equipment and paperwork, to replace, rig and test as required for return to service.
An LRU is the smallest component that can be removed from the airplane under the manufacturer's authority, aside from consumables and hardware. All designated LRUs will have a removal/installation procedure in the aircraft maintenance manual.
The next level up from "line" will be a certified repair/overhaul facility, a certified shop at the airline itself (a "back shop"), or the manufacturer of the LRU itself.
An LRU may have sub components that can technically be removed as separate units without removing the LRU from the airplane, but if that sub unit doesn't have its own LRU designation, you can only remove the larger assembly, that has the LRU designation, and any further breakdown of LRU into sub units is a back shop activity that requires a component maintenance manual to perform, with a separate regulatory certification requirement for the back shop.
For example, a hydraulic power control unit (PCU) may have a transducer installed on it that could easily be swapped out on the aircraft without removing the entire assembly, but without an LRU designation for the transducer, you are stuck with removing the entire PCU assembly and sending it to a back shop or offsite to have it repaired.
It's sometimes possible to get a sub component designated an LRU, with its own aircraft maintenance manual procedure, if that sub component doesn't require specialised back shop tooling, or a back shop functional test isn't necessary to validate the installation.
For electronics, you may have a black box, with separate circuit cards internally. Sometimes the individual circuit cards will be designated LRUs and the technician on the ramp can open the box and swap out the card using a maintenance manual based procedure. If the cards don't have LRU designations, the ramp tech can only swap out the box, the smallest component with the LRU designation.

I would imagine that "line" here (as in "line indoc," etc) is borrowed from the military. Wiktionary has line 1 sense 17: "(military) The regular infantry of an army, as distinguished from militia, guards, volunteer corps, cavalry, artillery etc." In the FAA there is similarly a distinction made between "line controllers" who actually work traffic and the front-office managers and support staff, or even controllers on support detail, who do not make up "the line." Indeed, until recently the supervisor of a line controller was a "Front-Line Manager"!

Yeah no doubt. It may even have naval roots, or maybe the old British phrase "thin red line".

Fun fact: for spare parts for the International Space Station, we use a similar nomenclature, except we call them ORUs -- Orbital Replacement Units

IBM called them FRU's for Field Replacement Unit.  The item was freighted to the user for them to do, rather than being hand-carried to site by an engineer who would do the replacement..

It refers to the flight line, in other words the ramp where aircraft are parked. The component is relatively easy to remove and replace.
Other parts require special tooling, jigs, cranes, and so. So a air data computer is a line replaceable unit. A vertical stabilizer is not.

In this context, 'Line' means the opposite of 'Factory': if something is 'line maintenance' it means that it doesn't require a return to the original manufacturer.

There are a couple of other levels between line & factory; you can have hanger or overnight maintenance, and then there is depot-level maintenance (which in practice can probably do anything that can be done to the aircraft; the factory itself may or may not do repair work at all).

@RalphJ  The number of levels in between "Front Line" and "Factory" is immaterial, and will vary according to the context anyway, but are still opposite ends of the spectrum in any industry.


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Is this electrical socket found in aircraft?
I work for a a Public Utility in IT Asset Management, and we have been buying these auto air  adapters (Dell's description) from Dell for our field workers. Each one comes with an adapter that goes between the cigarette lighter adapter for cars, and an unknown type of electrical socket that I have never seen before:

It has a four contact input:

One of my co workers suggested it might be for aircraft use? I would figure it's for either General Aviation Aircraft, Helicopters or Business aircraft, if it's for aircraft.

I've never seen anything like that, but that doesn't mean much in isolation.  Are you asking about charging from a passenger seat in the back of an airliner, or while riding in something small like general aviation Cessna/Beech/Cirrus/Piper/etc, or in helicoptors, or riding in something higher-end, like King Airs or business jets etc?  A more specific target in mind may attract answers from those most knowledgeable about those particular aircraft.

Not entirely sure, I would suspect not an airliner, since they appear to have something more consumer friendly (based on a different question) like 110v outlets. I would figure it's for either General Aviation Aircraft, Helicopters or Business aircraft, if it's for aircraft.

It appears to be this product. The description is not enlightening. https://www.dell.com/en-us/shop/dell-auto-air-adapter-90w/apd/450-aelt/pc-accessories

This is an EmPower Classic connector. It supplies 15 V at up to 75 W and saw limited availability on some aircraft, particularly in business/1st class. As far as I can tell, it's almost entirely obsolete/defunct and no longer promoted. It's been superseded by universal AC plugs and USB ports.
SeatGuru claims to track seats with this connector but with 5 minutes of poking around I wasn't able to find any flights where the EmPower Classic connector is marked available.

The intent of the proprietary plug was to limit use of the outlet to approved devices. I have an older version of the Dell car/plane power brick and the label says it's DO-160 compliant.


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What do you need to have onboard for flights with an ultralight/sport aircraft over water (Atlantic, Pacific)? Life raft possible (weight/size)?
Remark: For us in Germany an UL is a 2 seater with 470/600kg MTOW. AFAIK those are named Light Sport Aircraft in the US/Australia. Example: https://en.wikipedia.org/wiki/Ikarus_C42
What do you use if you fly with your UL/Sports aircraft over water? As a reference I did try to find out what other pilots have used:
Some people have surrounded the world with an ultralight aircraft. A recent example here: https://flyzolo.com/ Did they have a life raft onboard? Or is an Immersion Suit/Survival Suit sufficient? Or are there even other options?
Life rafts do not seem to be to heavy, but would it possible to deploy them after ditching? Or would it just be impossible to deploy such a raft in such a case?
I have also watched a YT series "FunForLouis World Flight", they have used Immersion suits. But the flight was in a Cessna 210 and the weight was already an issue. So I assume more restrictions with an ultralight/sports plane.

Edit 2022-06-22: This YT video shows a Cirrus with parachute ditching. Pilot manages to deploy a little raft before the plane sinks. So it seems to be feasible. Related: Why did this Cirrus deploy the parachute while ditching over Pacific Ocean?

Related:  But this is for "big" planes.

Has a life raft ever been successfully deployed on a modern commercial flight?
For routes over oceans, are slide rafts fitted with first-aid items, food, water, radio, etc?

Why would it be more difficult to deploy a life raft from an ultralight?

Normally you have very little storage room in an ultralight. And the raft needs to be quickly accessible from within the cabin, so the options are limited.

Your usage of "ultralight" differs from my understanding.  Perhaps you should describe what you're thinking of for an "ultralight".

The question, especially 1st pgraph, seems to be about what was done on a specific past flight.  The title seems to be more open-ended, about what is "needed" (by whose definition of "need" -- prudent avoidance of risk? meeting legal obligations?) for long-range overwater flights by "ultralights" (by whose definition of ulight? FAA definition limits empty weight to 254 pounds (115 kg) empty weight, excluding floats and safety devices, and "Shark" does not meet this definition.)  I suggest editing the title to be more harmonized to the question, about what was done on a specific past flight.

The UL point is valid. For us in Europe/Germany the term Ultralight is normally used for a 2 seater with a weight limitation: https://en.wikipedia.org/wiki/Aveko_VL-3_Sprint is a UL plane for us. According to WIKIPEDIA it is Light Sport Aircraft in the US or Australia.
Thanks for point that out!

I am asking what you are using when you fly long legs over water. But if you know what others use, also fine. The best example I have found is this video with a Cessna 210 as there is one episode where they get and test the suits.

@quietflyer I could not see what Rutherford is using, obviously she als avoided water as much as possible. In the 1st picture it looks a bit like she is wearing an Immersion Suit, but pure speculation.


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How much momentum is lost through the wheels when landing?
I am idly curious whether any significant proportion of a landing plane's momentum is lost through wheel braking vs. everything else like thrust reversers, aero drag, etc?
If I have to pick a plane, let's go with a 737.

Comments are not for extended discussion; this conversation has been moved to chat.

The vast majority of the stopping power on a landing is the wheel brakes.  Reverse thrust is a much smaller component, and as it happens is generally not taken credit for in published landing distance performance data. It's just a bonus. The pilot can choose to use reverse or not, and often won't, maybe only deploying them to idle reverse to have available just in case some braking power is lost for some reason.
Aerodynamic drag is significant at first, although still way less than wheel brakes, but quickly declines as speed comes down, whereas  wheel brake power (as in, what you feel as deceleration, not so much actual mathematical energy conversion) is relatively constant all the way to being stopped.
Brakes on airliners and generally split into two separate circuits on each gear, leaving half braking if a sub-system fails. If that happens, landing distance goes way up.
Then there's anti-skid (ABS in a car). Anti-skid is the only thing that allows the pilot to use maximum braking. Without anti-skid, going hard on the brakes will likely lock wheels and blow tires, because airliner brakes are like truck airbrakes, with no feedback at the pedals, just spring pressure, and you can only modulate them based on your sensation of deceleration of the plane.
So, the large majority of an airliner's stopping power is in the brake system, with the anti-skid system making it possible to exploit all of the potential braking power.

The OP specified in the comments that spin-up is not what they are asking about.

Well now that it's been revised...

Frictional braking power relies entirely on contact with good pavement. Ask a Minnesota driver about that.   Whereas thrust reversers rely entirely on contact with good air.   So unless God removes all air from the airport vicinity, thrust reversers will behave predicatably, if anything be higher performance in a rain squall due to higher thrust mass (the water).

Max reverse alone is like very lightly applying brakes. Even on a wet or compacted snow runway, most of the slowing power is coming from braking. If the plane has cascade style reversers that only direct air forward at a slight angle, they do almost nothing really. And you have to get the reverse off as the speed drops below 90-80 kt so it's only working during the initial part of the roll.

Thanks - this is the kind of answer I was looking for. I had assumed that reverse thrust was the lion's share of braking but I guess not!

When you say "wheel brake power is relatively constant", do you mean the physics definition of power, force * speed, the amount of energy per second the brakes can turn into heat?  Or do you mean near-constant force and thus acceleration, rate of stopping?  I'm guessing the latter, so you might want to edit to be more precise, especially given the physics discussion in comments under the question that had me primed to read it that way.

@PeterCordes Thanks for the comment.  Made a little edit.

Not much, as planes will never carry large heavy wheels into the air.  The concept could be tested with models. Some energy will be required to overcome the angular inertia of the wheel.
In olden times, this was known as a "flywheel".  This stored energy can be utilized, for example, to keep a piston engine turning smoothly between powerstrokes.
But with aircraft, weight savings is paramount.  To scale, any energy going into spinning up wheels on landing is miniscule compared to the kinetic energy of the aircraft.  And while we are at it, a bit of energy also goes into the "chirp" on touchdown from frictional heating, also found from braking.

I realize some bush pilots may disagree with the first sentence.

I don't think the question is about transferring energy to spin the wheel.  It is about using the brakes mounted on the wheels.

@FlorianF related, interesting enough to post.


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Did I witness an engine test for a 757 at MAN?
A while ago (Summer 2020) I was walking near MAN airport (UK) and saw a 757 taking off. There was a peculiar event during takeoff and I'd love to know what it was.
Once airborne at about 1000 feet (complete guess) its starboard engine started showing flashing rings of flames and there was a loud repeating banging sound for about 20-30 seconds. The plane continued to climb up to several thousand feet.
While watching this I opened FlightRadar and saw that the flight's destination was also MAN.
Over the next 30 minutes or so the plane did a few laps and presumably came back to land.
I'd love to know what this event might have been?

See this avherald report: https://avherald.com/h?article=4db1ccdb&opt=1

A Jet2.com Boeing 757-200, registration G-LSAN performing a test flight from Manchester,EN to Manchester,EN (UK), was in the initial climb out of Manchester's runway 05L when the right hand engine (RB211) emitted a loud bang and streaks of flame. The aircraft levelled off at 5000 feet and returned to Manchester for a safe landing on runway 05R about 25 minutes after departure.

So yes, it was a test flight, but it obviously did not go according to plan, resulting in an engine failure.

It seems it tested things they weren't planning on testing.

Thanks very much, nice resource at AV Herald

@FreeMan "We're returning to the airport" - "So the engine vibrations have stopped?" - "In a way..."

That's classic bird strike.

@JohnK Indeed, that's what I thought too...

@JohnK Given that it was a test flight, I wouldn't be surprised if it was an internal fault causing a compressor stall rather than an external cause. It's not uncommon for repairs to introduce new faults or not adequately address the initial fault - that's why they do the test flight.

What you describe sounds exactly like compressor surges following an engine failure of some sort (e.g. a bird strike during takeoff.)
Here's a video of exactly that happening with a 757 at Manchester (though back in 2007, not this year):

In short, this is the result when something (such as damage to the engine) causes abnormal airflow through the engine. When a compressor's blades stall aerodynamically, the back pressure from combustion can literally cause the engine to backfire (i.e. blow air and combustion products out the front.) This relieves the overpressure in the engine, however, if the issue that originally caused the compressor stall isn't resolved, the pressure will build up in the combustion chamber in excess of what the compressor is able to blow backwards again and the cycle repeats until either the issue causing the stall is resolved or the engine is shut down.
For a much more in-depth discussion of this process, I'd recommending reading mins' answer to the question If the intake of a running jet engine is blocked for some short duration what would be the sequence of events following it?


text:
Who controls mood lighting on a commercial airplane?
Who is in charge of controlling the mood lighting on commercial airplanes such as the Airbus A350 and Boeing 787? How is it controlled?

The cabin lighting is controlled by the cabin crew. There are usually control panels at multiple locations throughout the cabin, typically near an entrance door, where the cabin crew is seated.
On the Boeing 787, the cabin lighting is controlled via the Cabin Attendant Panel (CAP):

CABIN SCENE LIGHTING
The primary lighting in the passenger cabin is controlled in the CABIN SCENE
LIGHTING screen. Flight attendants choose from lighting scenes to set the cabin
lighting. Lighting scenes are short sequences of lighting changes designed to
transition to a level designed for various times during the flight.  [...]

(Boeing 787 Flight Attendant Manual 2A.15.3 - Cabin Services System -
LIGHTING - Cabin Scene)
The cabin area can be selected on the left and a new cabin scene lighting on the right. When START is pressed, a transition into the new scene lighting is initiated. The following scenes are available by default (others can be configured by the airline):

(Boeing 787 Flight Attendant Manual 2A.15.6 - Cabin Services System -
LIGHTING - Cabin Scene)

Out of interest: Are the transition times purely aesthetic? Or is there some specific purpose to them?

@pat3d3r: I'd assume that, in general, the gradual transitions are used because a sudden change in lighting would be more likely to startle and possibly alarm passengers. A gradual shift is less likely to be noticed, and even if noticed, looks deliberate and unhurried. A sudden change might cause some already nervous passengers to suspect a malfunction or an emergency of some kind.

… As for the specific transition times listed, the general trend seems to be that very bright or very dark settings have slightly longer transition times, which makes sense if you want to limit the maximum rate of change. The notable outliers are the "sleep" modes, where you presumably want to be extra careful not to startle passengers awake just when they're trying to get to sleep. The descriptions also suggest that there might be some fancy non-linear color transitions to "simulate sunset" going on there.

Do all 787 use this same cabin management system? Or are there various offerings, selected by the airline customer?

@grumpy1arrival others can be configured but the airline

Confused. I don’t see options for “Red Alert” or “Yellow Alert”? How do you effectively summon the crew to their battle stations?

@IlmariKaronen: Thanks for the comprehensive answer, this makes sense.


text:
Do we have orange runway markings?

As you can see in this picture, the runway markings are in orange or yellow.

I am confused by your question. The answer seems to be pretty clear: since there exists a photograph of orange runway markings, it is clear that we have orange runway markings. Or are you asking whether the photo is fake? That does not sound like an Aviation question to me.

In our country rules (Iran) we have only white markings for runway. Also I checked FAA and I understood that FAA rules as like as ours. https://www.faa.gov/air_traffic/publications/atpubs/aim_html/chap2_section_3.html

White runway markings that turn orange are affected by a contaminant in the aggregate of the asphalt.  There are modifications that can be made to the paint to resist the rust-staining.  A study by the New Hampshire Department of Transportation studied several paint formulas and had the greatest success with a stain-resistant paint formula manufactured by Safety Coatings of Foley, AL.  FHWA-NH-RD-26962T

Do we have orange runway markings?

Yes. We do, apparently.
Longer answer:
I didn't expect aviation.stackexchange would be similar to geoguessr, but this appears to be New Chitose Airport in Japan. The following Google Satellite view is approximately what can be seen in the photo:

It can also be seen in this Wikimedia Commons photo. Per a discussion on airliners.net, "in Japan they do have yellow/orange runway markings, but only in areas which get lot of snow... It seems that the use of orange markings only applies to civilian airports, as military bases seem to use white markings. For example in New Chitose Airport / Chitose Air Base, the civilian side has orange markings, and the military side uses white ones."

Thanks for your help. I checked my country rules and also FAA and just find white markings for runways as I expected. Btw, so is this only for Japan?

Norway does as well, rationale is that it's easier to see when there is snow on the runway. They have changed from yellow to white in the last 10 years.

Using Google Earth, I can see Norway's ENGM changed from yellow to white between 2015-2018. More unique: Thule Air Base's entire runway was painted white ~1960 to decrease permafrost melting. It had red markings until ~2012.

Thank you sir..


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Why are there no helicopters with the rotor mounted on the bottom?
Downwash from the rotor of a helicopter creates drag on the helicopter body acting against the lift force of the rotor.
Why are there no helicopters with the rotor under the main body of the helicopter to eliminate this force?

What does the helicopter land on? The rotor is still spinning when the helicopter is on the land, so the gear can't extend through the rotor. The hub is too small for the weight to be balanced on uneven ground. Having long arms for the gear that extend past the rotor might work, but would be ungainly

I think that's called a lawnmower.

Mandatory gif: https://i.sstatic.net/IqEqj.gif

If the rotor would be underneath the helicopter, then:

The helicopter body would still generate vertical drag from being exposed to the vertical airflow, but now above the rotor,
The rotor would work in a disturbed turbulent airflow, because of said body, increasing vibration and reducing efficiency,
You still need some landing gear below the rotor to land on.
The slightest roll control input during start or landing would cause a blade strike on the ground,
Uneven terrain would cause a blade strike
Loading and unloading passengers and goods would require the rotor to come to a halt first.
Whilst the helicopter is parked, the low rotor could easily be accidentally damaged by inattentive ground operations.
The body would need to be on a rigid mast above, instead of hinged below the rotor. From a stability point of view, this is challenging at least may be beneficial for stability.

In summary, putting the rotor below the helicopter has many downsides, but gives very few benefits.

Good answer, however your point 8 about stability is a counterintuitive misconception. The mounting point of your rotor in respect to your CoG actually affects the stability in a positive way. See this answer: https://aviation.stackexchange.com/questions/42513/would-a-helicopter-with-the-blades-on-the-bottom-fly-the-same-if-at-all

@U_flow thank you for the link. I have updated the answer accordingly.

One additional consideration for point #8.  Rotor masts are typically narrow metal cylinders, which are stronger in tension than compression.  The rotor attachment to the transmission would likely need to be radically different.

Another point - autorotate would be extra-difficult, with the pilot having to essentially "balance the broomstick" rather than hanging under it.  Noone needs that extra work when its all gone badly already.

Points 1 and 2 are if not entirely then at least mostly wrong. The air flow above a helicopter rotor is not supposed to be linearly downwards at all, on the contrary the whole working principle is that it directs air coming in horizontally (from the front during flight, from all sides during hover) downwards. It is true that the movement right above the rotor has a vertical component and would cause some vibrations, but nowhere near as much as that's the case for pusher props.

You also need a way to get over the rotor to board the helicopter unless you always plan to spool the rotor down to zero RPM when getting on or off...as well as having to walk through a rotor which you hope doesn't start up.

Blade strikes are possibly preventable with sufficiently computerized flight controls including fancy envelope protections, but it would be much harder to do something about FOD concerns. Putting your precious blades right into the middle of the cloud of kicked-up stones and stuff might not be the smartest move.

Actually, there are/were (nearly/sort-of)
Have a look at:  Lackner HZ-1 Aerocycle on Wiki

Interesting! So they invented the Breath of the Wild minecart flyer in 1955. "it was discovered that the Aerocycle's forwards speed was limited by an uncontrollable pitching motion,"

That thing looks terrifying.

That guy's not even wearing a chute, because, what's the point with that slicer underneath his feet.

Another one: https://www.hiller.org/event/flying-platform/

@CptReynolds And apparently the XMP-2 parachute, designed for the HZ-1 and VZ-1, "proved to have insufficient reliability for use as a personnel parachute".

Do we want to know how that XMP-2 parachute earned its customer reviews?

Some AAVs have the rotors mounted outboard and mostly below the cabin. Whether that's a 'helicopter' or not is arguable. Some definitions specify overhead rotor(s).

So it seems more practical when there are multiple (non-coaxial) rotors.

I would be so scared to get anywhere near one of these. Imaging accidentally falling or having one of those blades pull in a piece of clothing! they look cool though!

@coblr I imagine a practical air taxi version of that would not allow the blades to spin up unless the area around it was clear and doors closed. They're electric so they don't have to idle. It would have to have a lot of redundancy in the control systems to get approvals I would think.

@coblr How is it different to turbo prop planes?

@Darren: It's different because the rotors are so low that if you trip and fall, you could fall into them instead of under them.  And they're right next to the door because this thing looks tiny, unlike a typical turboprop.  coblr isn't just talking about not wanting to get near the blades, which is something you should avoid on any aircraft.  They're saying that there's no way to get near the whole aircraft without being near a blade.  So yeah, you'd want to make sure the blades aren't moving before opening the door from inside, or before walking up to it from outside.

@SpehroPefhany I'd be more worried about what can go wrong (externally, of course the doors can be interlocked) in the time it takes them to spin down again

The question might have been asked "Why do so few planes have pusher propellors?" The fallacious arguments in favor of them would have been answered in the same way.

@PeterCordes, yes, exactly thanks. Propellers are different because it's almost like a wall or something and they don't really take up much space in that respect. It's a "glass wall" in front of the wing, more or less. With these, and the blades spinning fast enough, you wouldn't really be able to tell where the edges were; you'd just feel air moving. Good calls out though on them most likely being completely off for boarding/disembarking or while doors are unlocked.

@Spehro Pefhany mentioned "outboard rotors", but I would like to mention an exotic example - AeroVelo human-powered helicopter. Its rotors are placed pretty low :-)


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What are these planes and what are they doing?
I know next to nothing about planes, so excuse any naivety below…
I live in Denver CO and frequently see military planes in what look to be training exercises. Today I saw two pairs of planes (one "big" and one "fighter") flying really close and am curious if the planes and/or exercise are identifiable. One pair disappeared behind the building before I could get a picture of both, so attached is just a picture of the trailing pair.

Mommy, what's that plane doing with that other plane?

If this is happening low enough that you can easily notice it from the ground and snap a clear photo (assuming you are not a news reporter or bird watcher etc who regularly carries around a camera with a long telephoto lens), it is probably being done for the benefit of people on the ground (air show, stadium flyover, etc) or as a rehearsal for such activities.


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Is the cabin pressure "worse" at the back of the cabin than in front?
My mother has a bad hearing problem and wears 2 hearing aids. She tells me the air pressure is worse for her in the back of the plane than the front. I would like to know if this is true - is there a difference in air pressure depending on where you sit in the plane?

She's right, she needs first class.

I remember running in an old bus long ago (~40 years ago and the bus was already quite old) where the acoustic resonance at some particular engine rpm gave me pain in the ears with some loud infrasound (I could feel the vibration). This happened only in particular place near the rear end of the bus. The effect was reproducible between different busses (they were the same make/model) and drivers. Bus drivers happened to like exactly this frequency / engine rpm for moderate uphills. This may or may not be related, modern airplanes should not have acoustic resonances this sharp.

I would guess that what she describes as air pressure is more likely the amount of flow coming from the vents.

Is this question better suited to Travel stack exchange? Since it concerns a passenger flying commercial? (Aviation is more about laws, how planes work, history of flight, etc).

@KevinKostlan ASE is the appropriate place in the sense that the question and answers deal with the complex and demanding sensory environment of aircraft.

The experience really is not about air pressure. We as humans have very few ways of actually experience air pressure. (Exceptions are things like congested vents from sinuses or inner ear, or gases in the stomach). What we mostly experience is changes in air pressure and they happen just about equally regardless of position in the cabin. But what does differ is sound, especially low frequency rumble from the engines. This, rapidly changing air pressure will be felt differently depending on position in cabin. Some aircrafts are worse (say SAAB SF340) than others.

@fraxinus funny, i recall a similar experience as a kid

As stated in other answers, in steady flight there is no pressure difference along the length of the cabin, and only a miniscule one during lognitudinal acceleration.
What your mother might be experinecing is actually low frequency sound/vibration that can sometimes feel like fluctuations in pressure, a sort of a bubbly feeling in the ears.
This will vary greatly on type of aircraft, seating position, stage of flight etc, but as such it is not at all implausible that in general your mother experiences this in the rear portion of the cabin more than in the front. This can be especially prominent in planes with wing mounted jet engines, since the exhaust nozzle will be in front of the passengers sitting in the aft section.

The key is to separate the symptom (discomfort) from the cause (air pressure). The discomfort is valid, the cause is a hypothesis. This answer offers an alternate hypothesis without discounting the symptom.

Yep. In medicine it's never appropriate to deem false symptoms a patient describes  simply because the inferred cause is implausible, or even totally out of the question. We still do not fully understand how human sensory systems work and especially how they intertwine with our psyche. Whatever we feel is always real in one way or another.

I agree vibration diagnosis.  Loud white noise is often described as "pressure" by people experiencing it.  Now, I disagree that wing mounted engines are worse.  From experience, rear mounted engines are beyond compare louder when sitting in the back.

My experience is different, but as this matter is subjective, your experience is as valid as mine. My recollection of rear engine noise is, that it is generally higher in pitch than that of  wing mounted engines when sitting at the back, and thus not as "bubbly" in the ears. There are a huge amount of variables here...

That is not possible. The front and back of the cabin are not isolated by any means - so if there was a pressure difference, air will instantly start flowing from high pressure to low pressure in order to equalise the difference.

A mass of gas in a gravitational field (for example, the Earth's atmosphere) has a pressure gradient in altitude. The same happens to a cylinder of air (for example, in an aircraft's passenger cabin) submitted to an acceleration... There will be an air pressure gradient between the front and back of the cabin...

@xxavier You are right, but let's calculate the difference. The Boeing 737-800 has a cabin length of ~30m. Let's assume the ISA MSL air density of 1.225 kg/m³. Upon being subjected to an acceleration of 4m/s² (typical during takeoff), we obtain a force of 4.9 newtons from that cubic metre of air, and thus a pressure of 4.9 pascals. Multiplying that by 30, we get a pressure of ~1.5 hPa at the rear-end of the cabin, so the difference is negligible.

I totally agree with negligible, but very few non-engineers regularly deal with  newtons, (other than the fig variety) or hPa.  Can you translate that measurement into something relatable like going up a set of stairs?  Most non fliers have experienced a change in air pressure going up in an elevator of a very tall building, or driving over a mountain pass.  Can you make a similar comparison with your math here?  (i.e. equivalent to a change of ____ feet in elevation...)

150 Pa is 0.15% of an atmosphere or a difference of 12.5 m (41 ft) in elevation at sea level.

@MichaelHall To put it another way, 150 Pa is about half the pressure that a single average chicken feather would produce if laid on an object in standard Earth gravity (assuming no wind).

@HiddenWindshield While that does sound like a low pressure, it does not give you any indication of how a human ear will react to such a pressure differential. Michael Hall has a point in asking for an equivalent elevation change.

@Raketenolli Different people understand different visualizations, so having multiple of them is not a bad thing.

While I would think there would be enough sound-absorbing materials in the cabin to limit the formation of standing waves, the front and back of a plane would be pressure antinode and the fundamental and all harmonics, while a point near the middle would be a pressure node for all odd harmonics.

@xxavier This would only be relevant if the symptom goes away during steady state cruising.

There may be other factors than a pressure differential as the cause of ear irritation, such as greater pitching accelerations, because the rear of the plane is farther from the center of gravity.  This could cause general motion sickness, and for some one with issues with their ears, in particular, the vestibular system$^1$, an increase in feelings of vertigo.
$^1$ see Pathologies

This is true. There's a lot going on inside the ear, and the sensations can get mixed up.

The difference in air pressure between front and back of the cabin will be trivial to the differences felt in pressurisation between the aircraft climbing and descending; or adjustments made to the ventilation controls.
Discomfort is far more likely to be due to the sound and vibration which will have a complex distribution depending on the type and layout of the aircraft and the extra motion typically felt  in the rear seats being noticeably more bouncy, and during acceleration and deceleration phases.
You might find the centre of the aircraft is the  best position rather than the front, and definitely not the rear.

There is a very small difference in air pressure, but only when the plane is accelerating...

That negligible difference would be offset by the equally negligible gradient in the other direction when the plane decellerates.


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Is possible to stick two '2-blade' propellers to get multi-blade propeller?
Does propeller blades' airflow interfere with each other blades and decrease overall thrust? Should I consider high pitch propeller for this purpose?
My purpose: I'm looking for a 20-inch four-blade propeller for a tail-sitter Drone. But commercially I don't find anything like that. So started looking at making a  4-blade/6-blade propeller with 2-blade propellers. Thrust density is my first priority compared to efficiency.

https://aviation.stackexchange.com/questions/53034/what-is-a-biplane-propeller-and-how-efficient-is-it

Increasing number of blades does interfere with each other but it does not decrease thrust. Quite the opposite it increases thrust (which is why you see multi bladed props). What it does decrease is efficiency (due to the interference). Meaning you burn more fuel for same amount of thrust. But you do get higher max thrust

Sure, this is not only possible, but even has some advantages over single-plane propellers. The catch is you ideally want the two to spin in opposite directions to cancel out torque and vibration.
You're building a contra-rotating propeller:

Pictured is a Sun Flightcraft contra-rotating gearbox kit for Rotax 503 and Rotax 582 engines.
Although more efficient (on the order of 10%) than single-plane propellers, they are also much more complicated to design. The gearbox will be heavier and harder to maintain. And they are also often much louder, although the Rotax kit pictured above is claimed to be quieter.
They're not just for small engines. Here's a Tu-95 strategic bomber:

On helicopters, the same idea is called coaxial rotors:

"Co-rotating" propellers are also possible, but far less common, as the key advantages (efficiency and cancellation of torque and vibration) are reduced or lost. I could only find some academic papers on it. Here is another.

Contra-rotating needs additional hardware. Just don't wanna do it because of complexity and cost. What about just literally sticking together?

@SRD Possible, sure. I don't know about efficiency. I was able to find a short paper on it but not much practical data. My gut feeling is as a hobbyist you'd be better off with a single-plane prop. I'm not an aerodynamicist though.

@SRD Oh, here you go! Masters thesis on it. Maybe that would help.

Pretty sure they're not building a contra-rotating system for a tail-sitter drone. These shine in the realm of high-end military hardware, but for a homebuilt, COTS availability beats efficiency.

@Therac yes... OTOH, a counter-rotating system for a drone isn't anywhere near as difficult to build as one for manned aircraft. Could be done basically with two plastic gears and a rubber band.

Alternatively, I wonder how well it would work to use the motor to only drive the differential rotation of the props, i.e. have the motor fixed to one of the props and drive the other one relatively to it, but both spinning freely against the fuselage. This would of course require brush contacts to supply the motor, but that's definitely doable.

Tu-95 uses some very cunning planetary gearbox, a very funny read, but I have displaced the link at the moment. Probably it's not relevant for a small drone.

It's done sometimes, for ultralight aircraft and paramotors. Like this:

Have also seen two 3-blade units joined in the same way to make a 6-blade unit.

That one's going to be awkward as the bolt circle doesn't align at 90 degrees, you'd really want an 8 hole bolt circle, or make a 6 blade prop.

@BrianDrummond: Would a 90-degree angle be optimal for blades that aren't coplanar?  I would think that a smaller angle would be better, since the propeller that's in front would take less time to clear the prop wash of the one in back than the one in back would take to clear the prop wash of the one in front.

@supercat You are correct. In a helix, putting a blade more forward requires it to advance to get closer to its original tip path.

@Brian Drummond  The finished two-blade units are first adhesive-mounted at 90º, and then drilled.

@xxavier That works. Though depending on the prop thickness and pitch, 90 degrees will not be optimal, per other comments.

Any propeller 'unit' has been designed for a certain set of conditions: rotational-speed/air-speed/power/etc.
If you then double-up in any way, then you can be assured that for the same conditions, the new unit will be less efficient.
Also, the most efficient unit, all things being equal is a single-bladed propeller - some small model airplanes use this setup because the tip speed is relatively low (supersonic top-speeds are "A Bad Thing") so designing a unit with extra blades for no good reason is also very likely to be less efficient.

A single-blade propeller has also been used on at least one manned ultralight-- I knew a guy who has flown such, but am unable to provide more details. On another note, in the examples mentioned in the related answer https://aviation.stackexchange.com/a/84188/34686 , it's possible that the units were designed specifically for use in this manner, for ease of manufacture or for economy in the event that one blade is damaged needs to be replaced.

The downside of a low number of blades is that you get less thrust for your diameter. Doubling up the number of blades on the same diameter WILL be less efficient, but it will give you more thrust for the same diameter and speed. It's a tradeoff: a large efficient propeller, or a compact less efficient one? It all comes down to the fact that momentum is mv and energy is proportional to mv^2. Reduce the area of the propeller and you end up needing to impart double the velocity to half the mass of air, which uses twice as much energy.


text:
Did WWII fighters do a roll before engaging to identify themselves to radar operators?
There's some folklore in the radar world about the Nazi fighters doing a roll before engagement to mark them to a German radar operator.  This makes a lot of sense because it allows you to change your backscatter signature and give a basic "friend or foe" signature to a radar operator.
I've been unable to find an authoritative source on this in the radar context; however, I have found reports of Nazis doing a roll, which leads me to two questions:

Does anyone know of an authoritative source?
Would a roll be executed for some other reason?

Edit:
The origin of this folklore is the following:  1) I heard about this from a lecturer when I was first doing basic radar design. 2) I heard about it from an American WWII pilot who was over Germany because I asked him after #1 (note: this was 20-some years ago).  3) I am currently reading a book that discusses radar and it is mentioned but unreferenced.
I asked around to other analog designers who do radar-type tracking, and we've all heard this folklore.  It's fundamentally how we do RFID tracking and the initial work was 1930s.
To that end, it seems that this isn't a very good question, and perhaps I need a historian.  It seems to be a question that if the Nazis rolled all as some initial move and then someone just assumed it was for radar.

Would a Wurzburg C or D be able to resolve a JU-88 30 miles away well enough to do that?  The ground based radars were mainly used to place the night fighters into the bomber stream. Targets were acquired by the on-board radar to within a couple hundred yards, and then visually by detecting the target's exhaust for getting in close enough to fire.

That theory doesn't pass the smell test. If it was that easy it's the first thing that the allies would have copied.

For a radar to be able to detect/recognize/distinguish the electromagnetic signature of a "roll" requires very sophisticated real-time Signal Processing, that was not available until digital computers were designed into and became part of the radar system, which did not happen until the late 60s and early 1970s (at the earliest).

That sounds like an answer @CharlesBretana

@CharlesBretana That's not true.   The roll could cause a "fade and huge blip" due to the capacitance on the line between the tube that is the receiver and the base-band mixdown.  I am an analog designer who has made some radars, and as far as technology, I am sure it would have worked circa 1940.  If it's folk lore, it is still feasible.

@bdegnan, yes I agree, but I do not believe this phenomenon would have been useable in the 40s. In the 70s, a technological capability called non-cooperative IFF (Identification, Friend or Foe) that attempted to use this phenomenon was investigated, and it was heavily dependent on Digital Signal Processing. I believe that for a radar operator in the 40s to be able to "see" this phenomenon on a raw radar display would be unlikely. Possible, but not likely.

@bdegman, Also, 1) the phenomenon would be heavily dependent on radar aspect angle, and 2) other things could also create the same "fade-in" and "fade out", so this phenomenon, even if an operator could detect it,  would not be a reliable indicator.

@CharlesBretana Due to the low quality of the radar systems, it's actually why I believe that this could be true.  You basically "pumped" the capacitors at an angle for targets.  As the radar aperture spun, you would have continue to add charge to bank for that division of the rotation when you had a reflection.  When a target changed aspect ratio, you would drain the voltage and cause the "blip" to disappear.    My question is about behavior and I'll update the question to reflect this.

In air combat maneuvering, turning is the fundamental tactic. You turn to move your velocity vector off your foe's flight path when you are on the defensive, and you turn to bring your guns to bear on your target when you are on the offensive. High-G combat turns start with a roll. So unless the closure is head-to-head (or very rarely, head-to-tail), the first thing every fighter does to engage (up to the present day) is roll to then execute a turn.

This question could be improved by referencing a specific source of this "folklore."

Also, as Todd mentions, almost every air-to-air engagement would start with a fairly aggressive, rapid roll, to set the wings for the first turning maneuver, but it would be unlikely to be a full 360 degree aileron roll.  Also just normal Combat Air Patrol (CAP) involves regular and frequent high rate of roll to set the wings to perform the turns to maintain CAP position and patrol orbits, which would be indistinguishable from a rapid roll used to initiate an engagement with an actual threat.

I'm guessing this is a reference to the classic WWII fighter "peel off" manouver, in which the fighters roll (and sometimes invert) before diving down to attack the bombers. I believe the Spitfire did it because its fuel cut off in negative g, but I don't know why others did. Or it may be just to change direction and dive at the same time. Here is a link: http://youtu.be/depF3lU-ADw?t=130

@DJClayworth,  This "peel-off" maneuver is done, again, simply to set the wings so that the lift vector (imagine an arrow pointing vertically out the top of the canopy) is pointed at the target. The lift vector determines the plane of the resulting turn (change in velocity vector) and to attack (or defend oneself) for any specific threat, you want to point at him, and/or rotate your vulnerable tail cone away from him. In either case, you put the lift vector on the enemy and pull on the stick to turn towards him. If he is below you, then.... well, there's your "peel-off" maneuver.

I think that could be an answer (or an addition to an existing one).

Note that lots of allied aircraft in WW2 had to roll before diving as their Merlin engines used carburetors, this meant that in a regular nose down the fuel was lifted out of the float bowl by the negative G's, starving the engine. This could be contributing to people thinking they would roll to identify themselves

I have never once heard of this-- doesn't seem right.

I can't imagine a WWII era German radar system being able to distinguish between a planned 360 degree aileron roll vs an allied (or German) snap roll to begin an engagement.   In the heat of an aerial battle there would likely be numerous "fades" and "huge blips" at each rotation of the antenna.

Another important fact is that the radars operated by the British in WWII did not rotate as modern radars did, they were more or less fixed cross-shaped antennae which could be only slightly adjusted in direction, and the operator used a device called a goniometer to estimate direction of the received signals.

For a radar to be able to detect/recognize/distinguish the electromagnetic signature of a "roll" requires very sophisticated real-time Signal Processing, that was not available until digital computers were designed into and became part of the radar system, which did not happen until the late 60s and early 1970s (at the earliest).
It could be conjectured that a very astute radar operator using a WWII radar that displayed raw returns, might be able to recognize the increase and decrease in radar signal intensity as an aircraft rolled, presenting a higher wing planform and radar cross section, in a roll, but that would only occur at beam (90 degree) cross angle, not head or tail on, not to mention that numerous other phenomena (weather, variance in transmitted signal strength, etc.), would probably cause the same variance. So it is highly unlikely that this would have useful or reliable.

Besides, how fast is the radar sweeping?  Even if ( IF ) the operator could see that "this" blip is a friendly, as soon as that aircraft merged with the formation of bombers, it's just a bunch of blips, with no ability to "track" the blip that earlier had rolled.  This sounds more like folklore than tactics to me.

Radar aside, do you have any idea why then a roll would be executed?  Is there some aircraft related thing like.. dunno, reset some fuel gauge or something?

They could identify themselves to other wings. If you assume most german fighters were involved in anti-bomber sorties, they would be up against escort fighters as well. Fighter groups would be scrambled from multiple directions and climb as high as they could before intercepting. During the sorties it'd be very hard to identify friend from foe unless very close. Wasting your whole fighter groups' energy to dive in on a friendly would be quite wasteful and dangerous.

@bdegnan, where did you see this roll maneuver mentioned? do you have a source? There may be other info in that source that offers a clue to why...

@CharlesBretana I expanded the question to better explain the folklore.

See my comment on the question.

I tried to find some info on why they did a roll, I found this https://www.airforcetimes.com/news/your-air-force/2018/06/20/screaming-bird-of-prey-how-the-ju-87-stuka-exceeded-its-life-span-and-carried-the-luftwaffe-through-wwii/ which calls it a "half roll" and indicates that some but not all pilots did it. They did mention having to brace to avoid hitting your head into the instrument panel when diving so perhaps rolling prevents that, plus I wonder if it allows the pilots to get eyes on the target earlier? Also I've seen spitfires do it in movies as well

@DavidWaterworth, that makes a lot of sense when entering a dive (in the referenced article with a dive bomber, but also for fighter attacking from above) – you have no downward visibility, so by rolling inverted first you can keep your eyes on the target below before starting the dive. You can also pull more positive G than negative (without fainting). Additionally in Spitfires the fuel system didn't handle negative Gs well, so that's another reason to roll and pull to enter a dive – but German planes didn't have that problem (as they already used direct injection).

To answer the question about tactical behaviour, I have no authoritative sources but I have elements. From this elements (that might be partial of course), it could be concluded that this behaviour might not be folklore, but not made before engaging:
Disclaimer: This answer assumes the manoeuver was feasible and efficient as a basic IFF method
Main use of radars by the Germans was for countering British night bombings. This included:

Detect the big formation of British bombers
Defeat the counter-measures used by them
Direct fighters to the bomber formation
At some point, let the fighters alone because counter measures do not allow anymore radars to pinpoint a target for the fighters, so it is up to the fighter pilot's eyes and on-board radar to find targets

The tricky point is the third part: the radar, facing a lot of spots that, from time to time, start to mix (because aircraft are closing on each other), needs to discriminate between them. So it could be a method to ask, from time  to time, the fighters to execute the "basic-IFF" manoeuver to discriminate them.
However, just after engaging, this would not have sense anymore to ask that. Because of the 4th point, the problem of German fighters was no more to be identified by ground radars, but to escape British night fighters and diligently shoot down the bombers. The fighters would act autonomously, without the helpof ground radars. It could only use the basic-IFF manoeuver again if it had pursued a bomber for a while and thus lost main formations. At that moment, the radar could ask him to identify in order to direct him again to the bombers or to its land strip.
Conclusion:
Probably not folklore, but not use "just before engaging", but more during the approach or recovery phase.


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What is this G1000 Flight Plan Symbol?
What does the horizontal flag on the G1000 flight plan page mean?

Thanks

I'm sure it is in the manual but I have not been able to find it. Standby for clearer picture

OP edited with higher res image

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What does a letter "R" means in a helipad?
What does it means when a helipads has a letter "R" and a arrow?
Here are some examples and the link to google maps:

https://www.google.com/maps/search/heliport/@35.4638657,139.6262343,40m/data=!3m1!1e3?entry=ttu

https://www.google.com/maps/search/heliport/@35.5238752,139.6749923,40m/data=!3m1!1e3?entry=ttu

Ⓡ is for Emergency Rescue/Response (not "restricted" as I thought first). According to this post on Quora: Buildings above a certain height are required to have such helipad. It is used in case of disaster, e.g. a earthquake, when streets are not usable to assist/to evacuate. This kind of requirement is also found in Korea, likely for the same reasons. According to another post, they are seldom used, and Volocopter is looking to use them as vertiports.

(Source)

i see, and do you know what the arrow means? I've seen some have one and two arrows.

@Gabe: I've no idea, possibly to indicate how to evacuate the helipad once landed.

If I remember correctly, those helipad cannot be used as normal helipad because they do not respect the minimum dimension for a helipad. They can only be used in case of emergency.

Im pretty sure the arrow indicates which direction the tail should point

I think the arrow is the direction the helipad should be approached, as to maximize clearance with the structure and surrounding buildings.

@user71659, are you sure? If I look at the 2nd satellite image in the OP, it seems like approaching from the South maintains more clearance to the objects on the roof than the east-west directions indicated by the arrows.

@ROIMaison Look at the image in 3D view. Approaching from the South would send the helicopter right into a giant cooling tower.


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Is there a common name for ailerons, elevators and rudder?
Since ailerons, elevators and rudder are all designed in a similar way, that is, they are attached to a fixed structure from where they move in both direction on that particular axis.
For example on a typical aircraft:

Elevator: On the horizontal stabilizer, moves Up and Down.
Aileron: On the wing, moves Up and Down oppositely
Rudder: On the vertical stabilizer, moves Left and Right

Is there a name in common we can call all of them?
Like in aircraft design/structure can we say that they are all X kind of thing?

Primary control surfaces is the typical name for ailerons, elevators, rudders, etc. Auxiliary flight controls include things like flaps, slats, slots, spoilers, leading edge devices, etc. Secondary flight controls are the same as AUX flight controls, just a different name.

"ailerons, elevator, rudder, etc." - what else is there?

It makes me think of elevons, wing warping, and stabilators. You could also count hybrids such as flaperons.

@Bergi canards?

Just to make sure, trimmable horizontal stabilizer would be a secondary control surface? It's not really primary, but at the same time, for pitch control, it's usually the only thing the AP would use, so for AP it's really primary...

@bergi The B-2 has control surfaces called elevons, so that would be another example. It also has a GLAS (Gust Load Alleviation System) which probably counts as a primary control surface

Trim is an interesting one.  It would be possible that you could lose control of say the elevator (snapped cable), but continue to maintain positive pitch control with the trim.  It would not be as responsive or accurate but it would beat the alternative.  On transatlantic / transpacific flights in the P-3 when the autopilot wasn't working (which was most of the time) I flew with the elevator trim.  It was a manual wheel vs electric so fine tuning with it was very easy.

@EarlGrey A canard typically has elevators. So the canard itself, like a horizontal stabilizer, isn't a control surface in such a case.

@HangarRash I do not think we can say anything "typical" about canards. See your canards (i.e. https://www.alamy.com/stock-photo-saab-37-viggen-thunderbolt-swedish-single-engine-short-medium-range-58657571.html ) and my canards ( https://qph.cf2.quoracdn.net/main-qimg-cac94e6500918b03d24676e1a9128a87 )
ps: I owe no rights on the here linked pictures, I will remove the links soon.

@EarlGrey Admittedly I was thinking primarily of canards like those seen on Rutan derived aircraft (Long-EZ, Cozy, Velocity, etc.) and not the type where the whole canard is a "little" rotating surface.

@Bergi collective, tilt...

All of the aileron, rudder, and elevator surfaces may be considered "aerodynamic control surfaces." This would also cover the primary, secondary, and auxiliary control surfaces, as noted by Wyatt.

Or even just "control surfaces".


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The FAA is asking for medical records that I don’t want to give. May I refuse?
My first class medical was deferred because I had optic neuritis due to a side effect from the covid vaccine. I was treated and my vision went back to 20/20. Now the FAA is asking for a vision test and MRI. I don’t want to provide the MRI since I think it’s a little excessive and could create new problems if anything else is found on it. Can I not send that in, and send in only the vision test with a note from my doctor?

I don't understand from the question whether this involves existing MRI records, or an FAA  request to take an MRI and submit those results.

They want me to send in an existing one

It has already been established in other answers you must provide the documents/information requested, else there will be consequences.
Also consider this: FAA is concerned with the overall safety of aviation. You also should.
Whether or not your MRI reveals anything out of the ordinary should not cause you worry, as I imagine a radiologist has already reviewed it, and found nothing. You are basically getting an extra consultation, and in the unlikely case something of concern is found, that plays in your favour: the medical condition found can be investigated further, and dealt with accordingly.
If you have a medical condition that renders you unfit to fly, you should not fly! Aviation authorities are not a mob hunting down innocent aviators to ground them just for giggles. To even think that is absurd. Do not play hide and seek with death.
Note: I've lost my aviation licence due to a medical condition. After the initial blow, I have fully accepted it. I wish not be a threat to my own, or the safety of others. Well, in the air that is. I still may act like an ass in the land traffic.

« you should also » :+1. First thing that falls apart, gets forgotten or mistreated is culture of safety

If the FAA medical division is asking for something on a deferred application, you have two choices: either send it and probably get your medical, or don’t send it and definitely be denied (and not be able to fly, even under BasicMed or Sport rules).
If they were willing to accept a note from your doctor in lieu of an MRI, they would have asked for that instead.

[MRI]could lead down another problem if anything else is found on it.

It certainly could, and no coincidence that the FAA wants to see it.  The MRI reveals information about a possible multiple sclerosis (MS) diagnosis within the next few years after an attack of optic neuritis (pages 186-7 here), and may even change the diagnosis from optic neuritis to MS. MS greatly increases the risk of new neurological symptoms in the future.  I assume the FAA cares about that, although they are not explicit here.  If so,  FAA physicians are unlikely to let the OP skirt that issue.

[@Jack Aidley] Do you really want to fly a plane with an undiagnosed
issue that would make the FAA ban you?

Modern MS treatments are extremely effective if started early, and that's one reason why MRIs are done, for risk stratification, in optic neuritis.  Either the treating physician was remiss in not explaining this to OP ... or OP isn't telling us all they know.  Not getting an MRI to avoid compromising a pilot's license would be the sort of poor judgment I'd not wish to see in the pilot of an airplaine on which I was a passenger.

+1. It's like 'not looking at the traffic light' to avoid running it while red.

I think you mean that the diagnosis of optic neuritis is an indicator that the patient has a higher risk of MS, right? Not that having an MRI will affect or increase the risk? (I am suggesting you [edit] your answer to fix your phrasing.)

@cjs That is true, but it's not what I meant.  I meant that having an MRI will affect the risk.  The MRI results actually.  With ON, risk of MS is greater than the general population.  Get an MRI, and that risk is shifted either up, or down, depending on MRI results.  MRI affects risk in the sense that it provides information on the probability of MS, not that it causes MS.  In this respect, it is no different from ON, which, as you correctly say, is an indicator of increased risk of MS, i.e. it provides information on the probability of MS.

@Scott: That's "will reveal additional information about the risk" not "affect the risk".  The risk is probability conditioned on what is, not on what you know.  Improving what you know will move the risk assessment closer to the true risk (and simultaneously decrease the uncertainty present in the assessment)

Scott, Ben is right, but even more important is that your post can currently be read as saying that the MRI itself is a risk-increasing procedure, similar to how an X-ray (very slightly) increases your chance of getting cancer. (In other words, read as "MRIs give you MS.") I am pretty sure that this is a) not correct, and b) you do not want to be saying or even implying this.

My optic neuritis was a side effect of the covid vaccine and was cleared up with some steroids. I’m still a student pilot so this is all new to me and I’m not sure how to navigate.

[@Shauna H] With respect to the FAA, I can't say, but with respect to your health, I suggest a long talk with a good neurologist.  The "good" part is important, but it's hard to know in advance who is good.  Your primary care provider has probably referred to neurologists in your area, and gotten feedback from patients, and may therefore know who are the good ones.  With luck, the upshot will be that you just had an isolated episode of ON and all of this is moot.

It is unclear in your question if you have already had an MRI, or if you wish to avoid having one.
You must release the records the FAA requested.  If there is no MRI to release, then you won't be supplying one.  They may subsequently ask for one, but it should be absolutely clear that you have not withheld any requested records.
The MRI record, if you have one, will consist of two parts.  The first part is the radiologist's report, which is easy to release.  Providing the image data is more difficult, and will require that you find where the image data is stored, contact where it is stored about their procedure, probably pay a fee, and get DVD(s) with the images.  They may require sending this directly to the FAA.  Some disks of image data are encrypted.
My experience is not based on dealing with the FAA, but instead because I needed to supply scans to a new medical practice.


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What causes pulses to appear in some contrails?
An aircraft at high altitude passed by faster and higher than normal, about 50% faster when compared to others in this recording. 2 mins later it appeared that half of the contrail developed right angle pulses evenly spaced along the contrail. It took about 7 minutes to clear. Is this normal? I have complete video. 2 pics attached.

A contrail is a cloud-like stream behind a high altitude jet aircraft, a con trail is what police dogs follow to capture an escaped prisoner.

But... What if the prisoner has hijacked a high altitude jet?  Eh?  Think about that one?  Ha!

I know I know, High Altitude Jet Tracking Dogs...

Clearly one of the mind-control-chemical sprayers had a partially clogged nozzle.

it's the lizard people sending coded messages

This phenomenon--which is not all uncommon-- is 100% meteorological.  On a day when conditions favor this, you'll notice this happening in most or all of the contrails visible, or at least in most or all of the contrails in a given altitude range.
You shouldn't assume that just because the phenomenon appears to involve only one side of the contrail, that one of the (presumably two total) engines is operating differently than the other.  If there is a wind shear, then parts of the contrail that ascend or descend will also move laterally relative to the main body of the contrail.  In the photo, the "puffs" appear to be descending relative to the main body of the contrail.  I believe I've also seen cases where the puffs appeared to be ascending, but would have to check old notes or photos to be sure.

Inferred due to fact that on days when it happens, it appears to involve nearly all the contrails that are visible.

When an object passes through a fluid, it can leave a Kármán vortex street.  The vortex street is a common occurrence, but it is only visible when the humidity is just right.

Your picture shows the contrail disturbed by the plane's vortex street.  The picture is taken from an odd angle that hides some the structure of the vortex.
Here is another example.

In 1992, Aviation Week reported on sightings of unusual contrails which were called "donuts on a rope" because they had evenly spaced puffs along a central line. The article speculated that they are the result of a "pulsed detonation wave engine", a propulsion technology which offers high efficiency at hypersonic speed.
Since then, there have been many sightings of such contrails and in many cases they were caused by conventional airplanes. The "donuts on a rope" speculation has been discredited as exactly this.
If you google for "donuts on a rope", you will find many more pictures and sometimes even a breathless comment that someone has spotted the airplane behind the black "Aurora" program. However, I am at a loss to explain how those contrails are made.

@RobertDiGiovanni I prefer not to engage in speculation because I have no detail knowledge here.

Good references, thanks.

Contrails are the same as the steam that comes out of you car's exhaust on a cold morning. It's condensed or crystallized water as a byproduct of burning gasoline or kerosene.
Therefore, I would say it's some kind of fuel control or airflow issue with one of the engines.  The contrails are ice crystals from moisture in the engine exhaust.  Certain temperatures and exhaust moisture levels will produce the contrail - drop below a threshold, and the contrail stops.
The puffs suggest that one of the engines has some oscillation in fuel flow or mass airflow, and the oscillation is taking the moisture level in the exhaust above and below the contrail formation threshold with each cycle.  It may or may not be noticeable to the crew, and may not even be a problem, as in engine malfunction, just a phenomenon that occurs when conditions hit a sweet spot.

Took the words righ out of my keyboard.

It’s quite possible that this kind of ‘standing wave’ or more accurately resonant airflow isn’t established until some distance behind the aircraft and so would be undetectable on the aircraft (and unlikely to be observed in a wind tunnel).

I’m going to speculate that the hot exhaust gases quickly cool and the water content freezes into small ice crystals.  Steam turning into ice contracts significantly and so clumps of water vapour may be pulled together into blobs that are visible from the ground, under certain conditions.  Under other conditions the ice crystals may remain more or less amorphous, although I can’t immediately say what conditions would favour the one over the other.

This is very plausible.

SR-72 I observed this phenomenon as you care to call it from a high altitude aircraft traveling northward over California. I call it high altitude because I was able to view an airliner at altitude, we're talking what 30,000 ft or so and the contrail in question was far above it also it's rate of speed well having no instrumentation to rely on I can only say was let's just say it was moving pretty fast. Incidentally Edwards Air Force bas is to the north of me. I also observed two other high altitude contrails that strangely enough exhibited none of the unique properties being discussed here. So let's speculate a little bit, higher than normal altitude higher than normal speed unusual contrail, interesting at the very least and wouldn't it just be grand.

Not an answer. These are anecdotal ramblings.

This does not provide an answer to the question. Once you have sufficient reputation you will be able to comment on any post; instead, provide answers that don't require clarification from the asker. - From Review

As pointed out in one of the answers this type of contrail has been seen with many types of aircraft including regular airliners. Possibly you saw this type of contrail in a high altitude military jet but there doesn't seem to be any definitive evidence that the phenomenon is based on the type of aircraft.


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What is the relation between airspeed and generated heat at constant drag?
I understand higher speed, and higher drag mean higher adiabatic compression leading to heating up the air, and the plane as result. X-15 needed ablative coating to prevent overheating. On reentry of space vehicles heat shielding is the most critical problem. This is perfectly understandable as higher speed with constant or growing air density means higher drag - and this results in higher speed.
I'd like to know how are these values related though.
[for the purpose of this question, let's neglect the issues of engine efficiency. We have a magical rocket engine that weighs nothing and needs no air nor fuel to produce thrust. This is a purely an aerodynamics question.]
At given pressure, drag is directly proportional to lift (both being quadratically proportional to airspeed and linearly to air density). That means higher airspeed allows raising the altitude, lowering air density, and thus lowering drag until lift and gravity even out.
Let's maintain such a flight: We're constantly accelerating (slowly); and climbing, at such a rate, that lift remains constant, and evens out with gravity (minus a minimal delta to retain climb). The increase of lift coming from rising airspeed is being offset by decreasing air density as the craft climbs.
With constant lift, and drag being directly proportional to lift, drag remains constant too.
Maintaining constant drag through climb like that, air density is inversely proportional to square of airspeed.
How would heat creation behave in this situation though?

A bit of a topic drift but pet-peeve: "minus a minimal delta to retain climb" - be careful, it's not excess lift that causes a climb in a steady-state climb. In fact ,lift is less than weight in a climb... search this site a bit for more explanations.

"increase of lift coming from rising airspeed is being offset by decreasing air density" - if you are 'accelerating' as in IAS is increasing, then decreasing air density is already taken into account (IAS vs TAS). What will happen is AOA will decrease to offset the increasing IAS (or TAS & q ) and keep lift constant

I'll leave a full answer to someone more math oriented, but generally heat (Q?) will be proportional with speed ^ 4. As you mentioned drag & lift is proportional to ^-2 . If you do the math you will see that spending a lot of time at high altitude can become a problem. Which is why most re-entries from space are not done by slowly decelerating at high alt, but violently dropping into the lower atmosphere

I'm definitely no expert on the topic, but this question/answer has the equation for "ram rise", which by definition relates the quantities that determine that temperature rise.

The situation for the X-15 and space re-entry vehicles (both hypersonic velocities) is different than for your example of a slowly accelerating climbing flight. Because of the hypersonic speed, shock waves are formed that have a huge energy loss in the surrounding flow. That energy needs to go somewhere, and most of it is converted into heat which affects the aircraft. At subsonic speeds, I don't believe aerodynamic heating is an issue.

You express a desire to simplify things by assuming a weightless rocket engine, so I follow with a weightless vehicle which only creates drag to overcome aerodynamic resistance.
This resistance has two parts: One is adiabatic compression when the air ahead of the approaching vehicle is compressed, and the second is friction. Friction shows up in strong shocks and in a layer of high shear stress around the vehicle which is called the boundary layer. Let's also neglect other heat sources like solar radiation which becomes more intense with altitude.
If we look at small changes, the adiabatic temperature rise ∆T due to a deceleration from a speed v to zero is:
$$∆T = \frac{v^2}{2\cdot c_p}$$
where $c_p$ is the specific heat at constant pressure (unit $\frac{J}{kg\cdot K} = \frac{m^2}{s^2\cdot K}$). The amount of heat Q which gets transferred to our vehicle depends on this temperature increase, but also on the air density $\rho$ and the flow speed:
$$Q = v\cdot\rho\cdot c_p\cdot∆T$$
Denser air contains more heat energy, so the proportionality with density should make sense. But why speed? If the hot air is replenished at a faster rate, more heat can be transported to the vehicle's surface per unit of time. Now we have a heat flow which grows with the cube of flow speed, but that is not all. We still need to understand how density will be affected. When air is heated, density drops, but the flow at the forward facing parts of the vehicle is compressed as well, so density goes up in the end:
$$\frac{\rho}{\rho_{\infty}} = \left(1 + \frac{\kappa}{2}\cdot Ma^2\cdot c_p\right)^{\frac{1}{\kappa}}$$
with $\kappa$ as the ratio of the specific heats and $Ma$ the Mach number of the flow. Now things get messy because all parameters will change with temperature, so let me short-cut to NACA report 1381 which covers the re-entry heating of spheres. Here the rate of heat transfer is proportional to the cube of speed, so flying faster at constant dynamic pressure will cause a quadratic rise in the temperature of the surrounding air and a rate of heat transfer rising with the cube of speed due to convection.

How do the units work out in $(\frac{v^2}{c_p} - 1)$? $1$ is dimension-less, so $c_p$ would have to be the same as $v^2$, namely $\mathrm{m}^2\mathrm{s}^{-2}$. But if it is specific heat, it is $\mathrm{J}\mathrm{kg}^{-1}\mathrm{K}^{-1}$. The $\mathrm{kg}$ reduces with the $\mathrm{J}$ to $\mathrm{m}^2\mathrm{s}^{-2}$ all right, but what about the Kelvin?

@JanHudec: Thank you - of course the equation was wrong. I should have looked it up properly.

A given airplane moving through the atmosphere at at given weight and velocity requires a specific and determinate amount of energy. That known energy can be expressed in foot-pounds, calories, btu's, etc. There are simple, straightforward conversions between these metrics. btu's typically represent heat energy.
A simple approach to determine the energy in foot-pounds is to fly at a known HP setting and fly for a specific time frame. The product of that HP times that time represents energy. Simply convert it to btu's.

Considering I don't have a supersonic airplane to conduct the experiment myself, would you care to provide the expected results curve?

Of course, not all of the spent energy will be transformed into heating by friction. A lot (actually, quite most) of the energy will be spent accelerating air downward and forward.

Temperature (Ram) rise is caused by air compression. It varies with True Airspeed.
I am retired now, but in my old notes for the B767 I have a formula.
Ram Rise (deg C) = V squared (KTAS) divided by 87 squared
For typical 470 Kt TAS it is 29.18 deg C.
I think that is right because we used a rule of thumb figure of 30.

Drag is negative air pressure (vacuum) behind the plane.
And wind resistance (increased air pressure) in front of the plane.
It maybe a misconception that heat is caused by "friction".  Friction can occur when you rub the same solid surfaces with some speed.
However, it's unlikely "friction" (widely held misconception, possibly) as it involves fresh, cold air (about -57 degrees C at 60,000 feet), gas and colliding into the wings.
It is possibly a chemical process involving various components of air (hydrogen, oxygen, nitrogen and carbon) and actually low level fire going on the leading edge (not confirmed) of the plane.
SR-71 at Mach 3.2 would experience heat in the range of 800 degrees at the nose, 620 degrees on the cockpit windshield.
A house fire ranges from 750 to 1,500 degrees Fahrenheit.

As it’s currently written, your answer is unclear. Please [edit] to add additional details that will help others understand how this addresses the question asked. You can find more information on how to write good answers in the help center.

To explain what happen at Mach numbers bigger than one there's no need to consider any "fire" or chemical combustion phenomenon: plain Navier-Stockes equations are enough to show that beyond a shock wave, temperature (in Kelvin) more or less doubles at Mach 2 and triples at Mach 3. So the SR-71 flying at Mach 3 at 220K (-50°C; -60°F) experience an air temperature of some 220x3=660K (390°C; 750°F).

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How much fuel aircraft should carry to complete flight plan?
Here is the question I was looking for (it didn't answer my question though), but this is specific to Boeing 787.
Is there any regulation to carry certain amount (may be %) of fuel aircraft should carry when its flight plan is prepared?
Note: We had argument that aircraft should carry 150% of fuel of it's planned travel, then someone bought argument of hijacking planes and said that 15 to 30 minutes of extra travel time fuel they have to carry.

Note that there is not legal/regulatory upper limit, but carrying extra fuel has a cost.

carrying extra fuel has a cost, but safety of the flight is on priority, right?

By extra, I mean past the lower regulatory limit described by @dave and the question linked above.

This may vary elsewhere in the world but according to the FAA FAR Sec. 121.639

Fuel supply: All domestic operations.
No person may dispatch or take off an airplane unless it has enough
fuel--

(a) To fly to the airport to which it is dispatched;
(b) Thereafter, to fly to and land at the most distant alternate airport
(where required) for the airport to which dispatched; and
(c) Thereafter, to fly for 45 minutes at normal cruising fuel consumption
or, for certificate holders who are authorized to conduct day VFR
operations in their operations specifications and who are operating
nontransport category airplanes type certificated after December 31,
1964, to fly for 30 minutes at normal cruising fuel consumption for
day VFR operations.